Apparatus for cooling electronics

ABSTRACT

The present invention relates to an apparatus for supplying heat to directly cooled electronics. To ensure that directly cooled electronics are maintained at a temperature above 0° C., a circulation fan is provided in a transverse junction between an outlet duct and an inlet duct, for a recirculation flow of supplied cooling air, whereby outgoing hot air from the electronics, when necessary, may be mixed with the cold air, so as to raise the temperature of the cooling air to be supplied to the electronics.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/SE01/0714, filed Apr. 2, 2001. This application claims the benefitof Sweden Serial No. 0001165-0, filed Mar. 31, 2000. The disclosure(s)of the above application(s) is (are) incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an apparatus for cooling electronics inaccordance with the preamble of claim 1.

BACKGROUND OF THE INVENTION

It is known in the art to enclose and directly cool electronics insidean outdoor cabinet by means of air taken from the environment. To thisend, air drawn into the outdoor cabinet via an inlet duct, passes by theelectronics to be cooled, and leaves the outdoor cabinet via an outletduct. The electronics emit heat to the air passing by, which increasesthe temperature, whereby the air leaving the outdoor cabinet gets ahigher temperature than the air which is drawn into the outdoor cabinet.

However, one problem arises at low environment temperatures, sinceelectronic components can be negatively affected by temperatures below0° C. By providing a transverse junction having a controllable valvebetween the outlet duct and the inlet duct, some of or all of the heatedair can be guided from the outlet duct to the inlet duct, whereby thetemperature in the inlet duct may be increased, thereby avoiding damagesto the electronics.

Such recirculation of air in outdoor cabinets is shown in GB 2,202,681and U.S. Pat. No. 4,495,545. However, these valves require engines orother equipment for controlling opening and closing. This is anexpensive and complicated solution.

SUMMARY OF THE INVENTION

This invention is directed to an apparatus as initially defined, andwhich is characterised in that a one-way valve is arranged in the outletduct to be opened under influence of the air pressure of the heated airacting on the valve, so as to discharge air from the outlet duct. At thesame time, a speed controlled fan is arranged in the transverse junctionto draw air from the outlet duct, thereby controlling the amount ofrecirculated air to the inlet duct as well as the amount of dischargedair leaving the outlet duct via the one-way valve. Hereby, recirculationof air to the inlet duct is simplified, since a passive control of thevalve is possible for the opening and closing. Passive control of avalve does not require any direct mechanical engagement or engine forthe opening and closing, and thereby does not require any automation andcontrol equipment nor any energy supply from engines. Thus, a simplifiedway for ensuring that directly cooled electronics are maintained at atemperature above 0° C. is provided since the air heated by theelectronics is mixed with cold air in the inlet duct, so as to increasethe temperature of the air which is supplied to the electronics.

Preferably, guiding ribs are provided in connection to the transversejunction. Hereby, air flowing through the transverse junction when thefan is shut off is avoided.

Suitably, a heater is provided in the inlet duct. Hereby, at lowtemperatures and at cold starts, heated air may be supplied to theelectronics.

Advantageously, a supervisory unit is provided to detect and registertemperatures in the inlet duct and the outlet duct, so as to control, independence of these temperatures, the number of revolutions of the fanand the supply of heat of the heater. Hereby, an optimal cooling of theelectronics may be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described by means of a preferredembodiment and with reference to appended drawings, on which:

FIG. 1 shows, in accordance with the invention, directly cooledelectronics inside an outdoor cabinet comprising a valve, a circulationfan for recirculation of outgoing air, and a heater, whereby theoperation is shown at a temperature above 0° C.

FIG. 2 shows the operation of the directly cooled electronics at anenvironment temperature below 0° C.

FIG. 3 shows the operation of the directly cooled electronics in FIG. 1at a cold start.

DETAILED DESCRIPTION

FIG. 1 shows an apparatus 8 for cooling electronics 1 in an outdoorcabinet 2. Air from the environment is supplied directly to theelectronics through a lower inlet duct 9 by means of a cooling fan 4 soas to cool the electronics. The heated air from the directly cooledelectronics is guided through an upper outlet duct 10 via a one-wayvalve 11 back to the environment air. The one-way valve is adapted tolet out heated air from the upper duct 10, but to prevent outdoor airentering the duct 10. The valve 11 is normally closed and is maintainedclosed by means of a spring 20, or alternatively, the weight of thevalve. If an opening occurs, a higher pressure must be present on theright side of the valve, so as to overcome the spring force or theweight of the valve. Accordingly, it is the air pressure of the air,which is heated by the electronics, that enables an opening and therebya discharge of air from the outlet duct. As soon as a sufficiently highpressure is no longer present, the valve 11 is closed under influence ofthe spring force or by its own weight. If a higher pressure is presenton the left side, the valve remains closed. A protrusion 18 ensures thatthe valve only can be opened in one direction.

Between the upper duct and the lower duct, a transverse junction 12 isarranged having a controllable circulation fan 13, such as a speedcontrolled circulation fan. In the lower duct 9 a controllable heatingdevice 14 is arranged, by means of which the air from the environmentand the air from the transverse junction can be heated, so as to securethat the directly cooled electronics achieve a minimum temperature. Bymeans of the circulation fan 13, outgoing air from the electronics maybe supplied to the cold air, which is drawn into the electronics. Thecirculation fan 13 may also be arranged so as to circulate air during acold start when neither the electronics 1 nor its cooling fan 4 are inoperation. An inlet and outlet of the transverse junction may beprovided with guiding ribs 15 or flanges for the guidance of the airflow. By means of a supervisory unit 16 the temperatures in the inletduct is detected, as well as the number of revolutions of thecirculation fan, and the supply of heat of the heating device.

When the outdoor temperature is above 0-5° C. the circulation fan 13 andthe heating device 14 are inactive, and the outdoor air is drawn intothe electronics 1 by means of the cooling fan 4 arranged in connectionwith the electronics 1. Hereby, the electronics are directly cooledwhereby the heated air is guided into the upper duct 10 and then to thesurrounding atmosphere, see FIG. 1.

In FIG. 2 the operation of the apparatus 8 is shown at an environmenttemperature below 0° C. At temperatures below 0-5° C. the circulationfan 13 is in operation. By controlling the number of revolutions of thecirculation fan, the amount of heated air to be supplied to the coolingair intended for the electronics 1 may be controlled along with thetemperature of the air passing by the electronics. At very lowtemperatures and low heat emission of the electronics, heat may besupplied to the air flow by means of the heater 14 in the lower duct 9.If the circulation fan 13 would break down, heating of the air may beaccomplished by means of the heater.

At cold starts, when the environment temperature and the electronicshave a temperature below 0° C., no heat will be emitted from theelectronics and its cooling fan 4 will not be in operation. By means ofa cold start function the electronics may be heated up to a temperatureof 5° C. In FIG. 3 the operation at cold starts is shown whereby theone-way valve 11 is closed resulting in a circulating air flow. The aircan then circulate through the electronics 1 by means of the circulationfan 13 and the air is heated by the heater 14. The one-way valve ensuresthat no air is drawn from the environment. Therefore, the circulationfan 13 is only drawing air from the electronics and blowing heated airto the electronics.

By means of the detection and registration of the temperatures insidethe inlet duct and the outlet duct, the supervisory unit 16 can beadapted to control the number of revolutions of the circulation fan 13as well as the heat supply of the heating device 14 so as to achieve anoptimal cooling of the electronics.

Suitably, some form of filtration of the air before it is supplied tothe electronics is arranged so as to protect the sensitive electronicsfrom contaminations.

What is claimed is:
 1. An apparatus for supplying heat at lowtemperatures to directly cooled electronics housed in an outdoor cabinetcomprising: an inlet duct for supplying outdoor air to the electronics;an outlet duct for removing the outdoor air heated by the electronics;and a transverse junction arranged between the outlet duct and the inletduct for enabling recirculation of the heated outdoor air from theoutlet duct to the inlet duct, the transverse junction including: aone-way valve in the outlet duct opening in response to air pressure ofthe heated air to discharge air from the outlet duct; and a speedcontrolled fan in the transverse junction to draw air from the outletduct to control the amount of recirculated air to the inlet duct and theamount of air discharged from the outlet duct through the one-way valve.2. The apparatus according to claim 1, wherein guiding ribs areconnected to the transverse junction.
 3. The apparatus according toclaim 1 wherein a heater is arranged in the inlet duct to heat airsupplied to the electronics.
 4. The apparatus according to claim 3further comprising a supervisory unit, the supervisory unit sensing airtemperatures inside the inlet duct and the outlet duct and varying theoperation of the fan and operation of the heater in accordance with thesensed temperatures.
 5. The apparatus according to claim 2 wherein aheater is arranged in the inlet duct to heat air supplied to theelectronics.